Self-diffusion was investigated by applying secondary ion mass spectroscopic techniques to heterostructures which consisted of molecular beam epitaxial layers that contained one or more stable isotopes of host crystal elements. Intermixing of the stable isotopes between epilayers of various isotopic compositions constituted near-ideal self-diffusion conditions; free from the complications of impurities, strain, electric fields and surfaces. When diffusion was investigated by using 69GaAs/71GaAs isotope heterostructures, the Ga self-diffusion coefficient in intrinsic GaAs under As-rich ambient could be described by:

D (cm2/s) = 4.3 x 101exp[-4.24(eV)/kT]

over 6 orders of magnitude at temperatures between 800 and 1225C. This suggested that a single defect mechanism controlled the process.

Self-Diffusion Studies using Semiconductor Isotope Heterostructures. E.E.Haller, L.Wang: Defect and Diffusion Forum, 1997, 143-147, 1067-78